Apparatus for spacing and uniting parts



Dec. 16, 1958 A. D. JOHNSON ET AL 2,864,935

APPARATUS FOR SPACING AND UNITING PARTS Filed July 1, 1957 7Sheets-Sheet 1 AW 03 mm EO VJ m D D E R F L A FLOYD K. COLLINS ATTORNEYDec. 16, 1958 A. D. JOHNSON ET AL 2,864,

APPARATUS FOR SPACING AND UNITING PARTS Filed July 1, 1957 7 Shets-Sheet2 INVENTOR ALFRED D. JOHNSON FLOYD K. COLLINS ATTORNEY 7 Sheets-Sheet 3z W m ,m. fir l 8 4 9 T I 4 9 8 9 Q 9 w? e v L M n .E m .w mm I 4 HI M J5% m w w INVENTOR ALFRIED 0. JOHNSON FLOYD K. COLLINS ATTORNEY Dec. 16,1958 A. D. JOHNSON ET AL APPARATUS FOR SPACING AND UNITING PARTS FiledJuly 1, 1957 Dec. 16, 1958 A. D. JOHNSON ET AL APPARATUS FOR SPACING ANDUNITING PARTS 7 Sheets-Sheet 4 Filed July 1, 1957 INVENTOR ALFRED D.JOHNSON FLOYD K. COLLINS ATTORNEY Dec. 16, 1958 A. D. JOHNSON ET AL2,864,935

APPARATUS FOR SPACING AND UNITING PARTS 7 Sheets-Sheet 5 Filed July 1,1957 INVENTOR ALFRED D. JOHNSON FLOYD K. COLLINS ATTORNEY Dec. 16, 1958A. D. JOHNSON ET AL 2,364,935

APPARATUS FOR SPACING AND UNITING PARTS 7 Sheets-Sheet '7 Filed July 1,1957 L. Q .L

United States Patent APPARATUS FOR SPACIN G AND UNITIN G PARTS Alfred D.Johnson and Floyd K. 'Collius, Seneca Falls, N. Y., assignors toSylvania Electric Products Inc, a corporation of MassachusettsApplication July 1, 1957, Serial No. 669,311

14 Claims. (Cl. 21978) This invention relates to apparatus forpositioning parts relative to one another and aflixlng said parts toeach other when so positioned. More specifically, this inventionconcerns itself with apparatus used to position and weld the parts of anelectron gun.

It is well known to those skilled in the art of electron dischargedevices that great care must be exercised during manufacture of suchdevices to space certaln of the electrodes relative to one another inorder that an acceptable product be obtained. In the case of cathode raytubes, it is necessary to closely control the spacing between the firstgrid and cathode inorder that the cutoff characteristic of such tubes bemaintained within certain desirable limits.

It will therefore be appreciated that in order to manufacture tubeswhose cutoff characteristic will fall within certain desirable limits, avery close check must be kept on all parts which could in any way affectthe distance between the control grid and the cathode. It w.ll further,be appreciated that a check of the grid-cathode spacing oneachgrid-cathode assembly after it is assembled andwelded together, butbefore incorporation within a tube, will result in a great sav.ng inlabor and materials by not incorporating improperly spaced gridcathodeassemblies into otherwise good tubes. For this reason, each and everygrid-cathode assembly is ch-cked for spacing before the gun assemblyoperation.

In a prior method of making the grid-cathode assembly, a circular metalspacer ring of L-shaped cross section is dropped into a cylindricalmetal grid cup with the flange end away from the bottom of the disc.Because of variations in the flatness of thebottom of the grid cup, areading is then made on a dial gauge to check the distance between theinside bottom of the grid cup and the outermostsurface of the flange ofthe spacer. Those parts showing improper dimensions are discarded. Thecathode assembly, which comprises a nickel cathode sleeve provided withan emissively coatedtop cap mounted in a substantially fiat circularceramic, is next measured for the height of the emissive coating abovethe ceramic. The cathode assembly is then inseited into the grid cup.The aforementioned spacer serves to space the cathode coating a properdistance from the grid. A retainer ring having a peripheral flange isthen machine pressed into the cup against the ceramic and welded theretoto thereby hold the cathode as embly rigid in the grid cup. A spacingcheck i then made by an air senser known as an air comparator to weedout any assemblies having an unacceptable'spacing between the grid andthe cathode coating.

The above steps-describe a method of manufactur ng and space checkinggrid-cathode assemblies which involves an undesirable number of handlingoperations and often produces a condition wherein assemblies are out ofspecification. This'condition cannot be accurately determined before thewelding operation.

It is an object of this invention to produce a method and apparatus formanufacturing grid'cathode assemblies cathode-grid assemblies betweentheassembling of parts 2,864,935 Patented Dec. 16, 1958 which willassure that the assembly is in accordance with specifications at thetime and after the cathode assembly is fixed in position within the gridcup.

It is another'object of this'inventionto continuously keep check on thegrid-cathode spacing'bymeansofiaa sensing device, so that a welder whichfixes the'ca'i'hode relative to the grid will be" energized only whensaid spacing is withincertain limits.

It is a'further object of this invention'to-eliminate checking of thegrid-cathode assemblies for spacing, asz-a separate step. 1

It is another object of thisinvention to incorporate spacing, checkingand welding ofsaid assemblies inone.

continuous operation.

It is a still further object of this invention to provide a method and amachine to eliminate handlmg' ofthe and the manufactured checkedproduct.

The features of the present invention which are believedto be novel areset forth with particularity in the appended claims. The invention,together with further objects and advantages thereof, may best be'understood, however, by reference to the-following descri tion taken inconnection with the accompanying drawings, in the several figures ofwhichlike reference numerals indicate like elements, and in which:

Fig. 1 shows, in enlarged cross-section, the grid-cathode assembly as itappears when inserted into anxair senser adapter'head ready to be spacedand welded .by the apparatus herein described.

Fig. 2 shows in enlarged cross-section thefinished grid-cathode assemblymanufactured by the presentapparatus,

Fig. 3 is -a plan view of the grid-cathode assembly shown in Fig. 2,

Fig. 4 is a plan view of a j gor adapter head hold'ng the grid-cathodeassembly in placeas it would appear during spacing and weldingo"erations.

Fig. '5 is an end view of the adapterhead looking int the assemblyreceiving end,

Fig. 6 is a section on the line 6-6 of Fig. 5.

Fig. 7 is a plan view of the adapter head receiving channel, a screwdriving mechanism for advancing the adapter head toward a hollowcylindrical st p, and welder electrode actuating means, a portion of theadapter head being shown in the channel.

F g. 8 is a side view of Fig. 7.

Fig. 9 is an end view of Fig. 7 takenalong the line 99.

Fig. 10 is a front view of the space checking air senser device showinga photo-diode in secti n, that operaes in conjunction with the ind'catorof the device totrigger welding, motor stop and reverie circuits,

Fig. 11 is a fragmental side view of the mechanism shown in Fig. 10 andalso showing photo-diode illuminating means,

Pg. 12 is a plan view of a three speed electrically controlledtransmission drive unit for advancing the lead screw mechanism shown inFigs. 7 and 8,

Fig. 13 is a side view of aportion of Fig. 12,

Fig. 14 shows a block diagram of the various circuits use-d to carry outthe objects of the invention, and

Fig. 15 is a schematic diagram of the circuits shown in block form inFig. 14.

The apparatus by which the objectives set forth; above are carried outconsists in its most elementalform of a grid-cathode assembly holdingdevice, means for advancing at a high forward speed the holding device,with respect to a stop in order to eifect a preliminary spacing oftheassembly, means for subsequently advancing the holdingdevice at a slowerspeed to effect a slower rate of change of the assembly spacing, sensingmeans 'affixed to one end thereof.

:cap carries an electron emissive coating 14. The cathode to stop thechange of spacing at a proper time, welding means to unite the grid andcathode at the proper spacing as determined by the sensing means, andmeans to return the mechanism to the starting point.

Description of the device Now referring to the drawings with greaterparticularity, Fig. 1 shows a grid-cathode assembly. The grid member ofthis assembly is to be accurately spaced from, and welded in spacedrelationship to, the cathode 11. The cathode comprises a metallic sleeve12, preferably of nickel, and having a cylindrical nickel cap 13 The topflat surface of the is secured within a central opening of a circularceramic member 15 having a recessed annular portion 16, and a pluralityof apertures 17 through said annular portion. The member 15 is mountedwithin a spider retainer comprising an annulus 18 having resilientfingers 20 projecting from the annulus. Also projecting from the annulusis a pair of diametrically opposed securing fingers 22 which are to bewelded to the wall of the grid cup 10. The grid comprises a metal cuphaving cylindrical walls 24 and a centrally perforated bottom 25, theexterior of the cup having wings 26 or the equivalent for latersecurement'to other parts of the electron gun structure. The spiderretainer, which holds the ceramic mounted cathode, is slidably,frictionally engaged by the inner surface of the cylindrical metal wall24 of grid cup 10 as clearly shown in Fig. 1. The grid-cathode assembly,with the cathode thus in adjustable relationship within the grid cup, isthen ready to be inserted into a holding device and to be operated on bya sensing, spacing and welding mechanism.

During the spacing and welding operations the gridcathode assembly isheld by the specially designed adapter head holding mechanism shown inFigs. 4 to 6. The outer member of the adapter head 27, is made of ametalblock 28, which is preferably cylindrical in shape to ride in asemi-cylindrical channel guideway, as will later appear. The block 28 isclosed at one end 29, the other end being threaded at 30 to receive acylindrical flanged end member 31. A washer 32 is seated betweenadjoining faces of the block 28 and member 31. The member 31 is providedwith an in-turned lip 33, having a recess therebeneath. Seated in therecess is an 0 ring 34, preferably of neoprene, and to effect an airtight seal around the curved edge of the grid cup 10.

At one end of the flanged member 31 and further outward from the O ringis a collar 35, having a number of bayonet slots 36, of which there areat least two and preferably three. These slots receive or grasp thewings 26 which are disposed on the periphery of the grid cup 10. Theslots have tapered walls 37 which assist in making an air tight sealbetween the neoprene 0 ring and the grid cylinder by rotating the gridcylinder whose wings 26 rest on the tapered walls 37, to thus press thecurved edge of the grid cup against the 0 ring.

Disposed coaxially within the cylindrical piece 28 and in axiallyslidable relation therewith is a compression cylinder 38, Fig. 6. Oneend of this cylinder serves as a seat for the O ring 34. The other endrests against the surface of a cam which is aflixed to a shaft 41, thelatter being held by member 28. The axis of this shaft is alsotransverse to the cylinders 28 and 38and suitable means is provided atone end of the shaft to receive a wrench or other device in order toturn cam 40 and thereby shift cylinder 38 with respect to cylinder 28.This action will compress the O ring 34 between cylinders 38 and lip 33thus compressing it against the outside of grid cup 10 to efliect. anair tight seal around its periphery.

The central part of cylinder 38 is provided with a bore 42 whichcommunicates with the end of the cylinder in contact with the O ring andwith a port 44, the latter being threaded to receive an air hoseconnection. At diametrically opposed points on the periphery of theouter cylinder 23 are guide pins 46 to maintain it in nonrotatableposition when resting in the channel to be described.

Referring now to Figs. 7, 8 and 9, means are shown for reducing thegrid-cathode spacing of the grid-cathode assembly and welding theassembly when said spacing is reduced to the desired dimension asindicated by appropriate sensing means. The numeral 60 indicates a baseplate upon which is mounted a guideway channel 61 having a way 62,preferably half-cylindrical in crosssection, that will allow the adapterhead to be conveniently received and advanced axially thereon between anadvancing push-rod shaft 63 and a positioner or stop member 64 at oneend of the guideway channel.

A hollow cylindrical shaft lead screw 66 is threaded into a stationarythreaded support portion 68 of the guideway channel 61 and an unthreadedportion finds bearing in a support 69. The thread must have a largenumber of turns per inch, being desirable, so that the axial movement ofthe screw shaft will be slow. This is necessary since the grid-cathodespacing is of the order of several thousandths of an inch; the inertiaof the various rotating driving members could easily overshoot thecorrect spacing if a much smaller number of threads per inch were used.

The push-rod or shaft 63 is disposed concentrically within the leadscrew shaft 66 and extends beyond both ends thereof. One end of the rod63 is adapted to engage the end 29 of the adapter head holding means 27and is a part of the moving means which urges the adapter head along theguideway channel 61. The other end of the rod 63 is fitted with aknurled knob 70 so as to be easily grasped. The push rod is axiallymovable along the length of a slot 72 in the lead screw shaft wall andcan move only the length of the slot due to a protruding pin 74 on therod. An offset bayonet type slot portion 76 is also provided in order tohold the push rod in its most forward position at which point theforward end of the push rod will either be in contact with or close tothe end wall 29 of the adapter head 27 as it rests in channel way 62.The sliding feature of the push rod is manual and its purpose is toprovide for quick axial travel of the push rod to thereby enableimmediate removal of the adapter head from the way 62 without waitingfor. the relatively slow axial travel of the lead screw assembly. Asimilar time saving is realized between insertion of the adapter headand the subsequent operations.

At an intermediate point on the lead screw 66 there is aflixed a pulley78. A roller 80 rides on one side of the pulley and is attached to oneend of a crank arm 82. The arm 82 is fixed on an oscillatable'shaft 84pivoted in a bearing 86, the shaft having a second crank arm 88. Asimple lever arrangement also might be employed instead of the foregoingmechanism. Attached to the free end of arm 88 is a tension spring 90,which holds the roller 80 against one side of pulley 78. Backward axialtravel of the lead screw and pulley forces arm 88 to actuate a limitswitch 89 and forward travel allows the spring 90 to pull arm 88 againstthe arm of another limit switch 91 to thereby actuate the same.

At one end of the channel member 61, and fixed to the base plate 60, isa rectangular block 93. in this block and extending therethrough isa'cylindrical metal tube 92. The end 64 of this tube is of smallerdiameter than the main portion and is adapted to engage the annularrecess 16 of the cathode ceramic 15 to thus act as a stop member. Saidstop member cooperates with the advance of lead screw 66 to reduce thegridcathode spacing to the desired value. As the spacing between gridand cathode is decreased, the grid cup slips ever t e l g diame erportion of tube 92.

Held with- The'block 93 has fixed to one side thereof two rectangularblocks 94, by means of bolts 95. These blocks are recessed to receivethe horizontally disposed and oppositely actuated sliding members 97,which are electrically conductive. These members are confined to theblocks 94, which are electrically non-conductive, by means of straps 98,and screws 99, allowing movement only along the longitudinal axis ofsaid members. The outer ends of the sliding members 97 are positivelyconnected toair cylinders 100 by means of connecting members 101, 102and 103. The member 102 is of insulat- 'ingmaterial to isolate theWelding current from traveling into undesired paths. Affixed to theinner ends of sliding members 97 are rollers 104 which serve as weldingcontacts.

Cable means 105 'connect'the sliding members 97 to terminals 106 on aterminal block107 mounted on the base plate 60.

Another cable 108 is connected from a central terminal 109 on terminalblock 107 to one end of tube 92. Through the tube at this end is alsoprovided a pin 110 to prevent axial movement of the tube when it servesas a stop for the cathode portion of the grid-cathode assembly. The pin110 also extends through member 111 which is secured to block 93 bymachine bolts 112. The tube 92 is of course insulated in suitablefashions, such as by means of an insulating sleeve, not shown, or bymaking the block 93 of an insulating material, so that the weldingcurrent will be routed through the proper conductors. The terminals onterminal block 107 are connected to a suitable welding power transformer280, Fig. 15.

At the proper time for welding, air pressure will be applied tocylinders 100 from a suitable air line, not shown, as will later appear.This will force rollers 104 against the wall 24 of the grid cup it;which is to be Welded to the securing fingers 22. During welding, thecurrent will travel from the secondary of the welding transformer 280,Fig. 15, to terminal 166 on the terminal block 197, through cables 165,through sliding members 97, through rollers 104 through the wall 24 ofthe grid cup and the securing fingers 22, thereby welding said well andsaid fingers together, through tube 92, through cable 108 to terminal1G9 and thence returning to the secondary of the welding transformer.

At some later time when the air to cylinders 100 is cut off, the springs114, compressed against stops 115 and members 102, will retract thesliding members 97 and rollers 104 away from the Welded grid-cathodeassembly.

The air cylinders 1% are connected to any air line of suitable pressure,for example 30 pounds per square inch, through a weld air solenoid 116,Fig. 15. This solenoid is actuated by the electrical control circuit tofeed air pressure to the air cylinders at the proper time beforewelding.

The sensing device by means of which the proper gridcathcde spacing isdetermined is shown in Figs. 10 and 11.

basic mechanism consists of a standard air comparator. This air senseris well known in the tube manufacturing industry for readinggrid-cathode spacing of cathode ray tube assemblies by means of changesin air pressure. The unit is, however, modified as shown in Figs. '10and 11 to adapt itto carry out the purposes of this invention. Thestandard air comparator comprises a casing 12%} carrying a face plate121 with a scale 122 and a movable indicating pointer 124; to assist incarrying forth the objects of the invention, a light 'ofi'the pointer sothat the beam from the light source 126 willbe reflected onto thephoto-diode 130 mounted in a housing 131 on a ring 132 on theperipheryof the source, mirror and photo-diode are added. The lightcasing 120. The peripheral location of photo-diode will depend upon thedesired grid-cathode spacing. Accordingly, ring 132 may be maderotationally'adjustable about the casing by means of a tongue 134 andslot 136 arrangement to allow location of the photo diode at differentpoints with respect to the dial. A set screw 133 is provided to fix thelocation ofthephotodiode at any point. Thus the photo-diode may berendered conductive by impingement of light thereon at any desiredreading of the pointer. In this way the mechanism may be employed toweld different electron gun type assemblies at their own particulargrid-cathode spacings.

In order for the air senser to sense the decrease-in spacing between thecathode coating 14 and the grid cup 16, an air line is provided betweenthe air senser and the adapter head. The air senser operates-on apressure of about 5 pounds per square inch but it may be connected to astandard air line of higher pressure, through an appropriate pressurereduction valve, not shown. The air flow through the system will then beas follows: first through the air senser, secondly through a flexiblehose connection and into the bore 42 of the adapter head, thirdlypassing through the aperture in the bottom 25 of the grid cup 10,through the spacing between the cathode coating and the grid, andfinally through the three holes 17 in the cathode ceramic 15, into theatmosphere. The neoprene O ring 34 in the adapter head prevents anyleakage of air past the outside of the grid cup and thus insures thatthe entire air flow passes through the grid-cathode spacing. As thisspacing is decreased, the impedance to the flow of air through thesystem will be increased and this increase will be sensed by the wellknown air senser mechanism and will actuate the pointer 124 thereon. Atsome predetermined position of the pointer, the light beam from thelight source 126 will be reflected into the photo-diode 130 by means ofthe mirror 128, to actuate various circuits as will later appear. Thescale 122 of the senser may be calibrated in thousandths of an inch fordirect reading of grid-cathode spacing.

In order to drive the lead screw shaft 66 at the proper speed in theforward and reversedirections, a special three speed transmission driveassembly, see Figs. 12 and 13, is employed. The assembly is enclosed ina housing 200. The input shaft 202 extends from one side of the housingthrough the opposite side and is fitted with a pulley 204 for beltconnection to another pulley, not shown, on a suitable driving means, asfor example, an electric motor. The output shaft 206 is disposed atright angles to the input shaft and on a different level. It extendsfrom one end of the housing, through the opposite end and is fitted withpulley 208. This pulley has teeth as does pulley 78 on the lead screwfor positive driving action by means of a toothed belt between them.

Associated with the output shaft 206 are standard magnetic clutch drivemechanisms 210, 232 and 214 and a magnetic brake 216. The clutches 210and 212 when actuated through energization of appropriate circuits allowa gear arrangement to turn the lead screw shaft 66 at fast forward andslow forward speeds, respectively, of 48 and 16 revolutionsper minute.The clutch 214 allows for a reverse speed of 64 revolutions per minute.The gear trains which produce these speeds are: (1) fast f-orwardinputshaft 202 via a spur gear 218 which drives a spur gear 220 fixed on ashaft 222 on which a worm'224 is also fixed, to drive a clutch body 226;(2) slow forward-input shaft 202 via a spur gear 230 which drives a spurgear 232 fixed on a shaft 234 on which a worm gear .236 is also fixed,to drivea clutch body 238; (3) reverseinput shaft 202 via a worm 242which drives a clutch body 244. The clutch bodies 226, 238 and 244continuously rotate in close proximity to their mating elements 228,240, and 246.

' discharge type.

respectively, which latter elements are fixed to output shaft 206.Various circuits actuate the various standard clutches at differenttimes to cause the appropriate clutch body to drive its mating portion.The circuit arrangement is so designed that if one clutch be actuated,no other can be actuated unless and until that one clutch has beendeenergized, thus avoiding damage to the assembly unit. The magneticbrake arresting means likewise cannot be actuated if any other clutchbeenergized.

The circuit for automatically carrying out the steps of the invention isshown in block form in Fig. 14. The photo-diode 130 and its cooperatinglight source 126 is shown in conventional circuit arrangement in Fig.15. The photo-diode 130 is connected by a plug 249 and socket 251 and acable to the input circuit of photo-diode amplifier 252; by this meansthe lamp 126 is also con nected to a low voltage power transformer 253.A sensitive relay 274 is connected in the output circuit of tube 255 andcontrols the action of relay 275.

A welding circuit in block 258, is of the condenser The welder, locatedon the base plate 60, receives its power from the control circuit bymeans of a plug 259, socket 261 and cable arrangement, Fig. 15. Whenrelay 278, is actuated, the circuit comprising the primary of thewelding transformer 280 in series with power storage condenser 282 andheat control resistor 284 is complete, thus discharging condenser 282.

The various magnetic clutches on the transmission drive assembly areconnected by a plug 305, socket 307 and cable arrangement, to thecontrol circuit of Fig. 15. This means also affords connection to limitswitches 89 and 2;, push button start switch 306 and the weld airsolenoid A timing circuit 256 includes a relay 286, capacitor 288,resistor 290 and a rectifier 292. This timer assists in actuating thewelder at the proper time.

To operate the various circuits a power supply having a full waverectifier 294 and a half Wave rectifier 296 is employed to supply directcurrent. The circuit includes a conventional high voltage transformer297 and filter circuits.

The operation of the system is made possible by means of a magneticallyactuated stepping switch 298 having seven positions and six circuits orbanks, four shorting and two non-shorting. Counting from the left, thefirst three banks are shorting, four and five are non-shorting, and sixis shorting. The various circuits actuated by the advancement of theswitch contacts will be described under the description of operation tofollow. A relay coil 300 is provided as a part of the switch, with aninterrupting contact 301, to actuate the switch to subsequent positions.A push-button 302 is provided, however, to manually advance the stepswitch when desired. Main power to the entire circuit is controlled by asingle pole single throw switch 304.

Operation of the device Operation of the apparatus is as follows: Aceramic mounted cathode, held within the spider 18, is inserted a shortdistance into grid cup 10, see Fig. 1. This gridcathode assembly is nextinserted into the recess of the adapter head 27 against the neoprene Oring 34, see Figs. 4, 5 and 6. Turning the assembly several degrees willengage the wings 26 on the grid cup with the tapered walls 37 of slots36 on the adapter head, thus holding the assembly firmly in position.Turning cam 40 via a suitable wrench applied to the end of the shaft 41then effects an air tight seal between the 0 ring and the outside ofgrid cup 10.

The assembly must be inserted in such a position that the securingfingers 22 on the spider retainer 18 are in line with the guide pins 46on the adapter head, so that said fingers will be under the weld rollers104 for the welding operation. The adapter head is next laid in thesemicylindrical adapter head channel way 62, see Figs.

' diode, thus activating the latter.

7, 8 and 9, so that the annular recess 16 of cathode ceramic 15 eitherengages or is in close proximity to stop 64 at one end of the channelway. The push rod 63 iS then advanced and turned manually until its pin74 engages the offset slot 76 in lead screw 66. The push rod is thusfixed against axial movement with respect to the lead screw. 7

The switch 304, Fig. 15, having been previously thrown, the circuits areenergized for automatic operation. It will be assumed that an assemblyhas just been spaced and welded and the step switch will therefore be inposition #1, the brake clutch 216 thus being energized. Also, the limitswitch 89 will be in closed position and limit switch 91 will be open,by reason of the reverse travel of lead screw shaft 66. Details of theoperation ofthe device are best understood with reference to the variousstep switch positions.

Step switch posiliOn #1 .The series of automatic operations is nowstarted by operating the push button switch 3%. This energizes the stepswitch coil 300 which advances the step switch to position #2.

Step switch position #2.In this position, bank #1 o the step switchfeeds power to the motor which drives the three speed transmission unit;it remains energized for all positions of the step switch from position2 to position 6 inclusive. Bank #4 energizes the magnetic clutch 210which allows the motor to drive the lead screw shaft at the fast forwardspeed of 48 R. P. M. This will advance the grid-cathode assembly in theadapter head traveling along the guideway 62, toward stop 64. After thecathode ceramic abuts said stop, the grid-cathode spacing will uniformlydecrease.

Bank #5 establishes a circuit path to the step switch coil 300 throughlimit switch 91, Figs. 7 and 8, so that when the lead screw shaft 66actuates said limit switch by means of the pulley and oscillatable shaftarrangement 78, 8t), 82, 84 and 88, said coil will advance the stepswitch to position #3.

Step switch position #3.Bank #2 energizes the primary of transformer 253which supplies current to photodiode lamp 126. It also connects power tothe weld air solenoid 116 which supplies air pressure to air cylinders109 thus forcing weld rollers 104 into contact with the grid cup, orwith tube 92 if the cup wall 24 has not yet advanced far enough to bebetween the rollers and the tube. These conditions are maintained forpositions 3, 4 and 5 of the step switch. Bank 3 connects B-lpower to theoutput circuit of the photo-diode amplifier tube 255; this conditionalso remains for positions 3, 4 and 5 of the step switch. Bank 4connects power to the low forward magnetic clutch 212 on the three speedtransmission, through the relay 2'75, allowing the lead screw shaft 66to now be driven at the slow forward speed of 16 R. P. M. The high speedforward clutch is deenergized when the step switch leaves #2 position,thus preventing damage to the transmission assembly. Bank #5 establishesan open circuit to the step switch coil 300, through the open contactson relay 275; the step switch will not be advanced to the next positionuntil relay 275 is actuated.

At this point the lead screw 66 continues to be advanced' at the slowforward rate of 16 R. P. M., continuously decreasing the grid-cathodespacing. The air flowing through the grid aperture will therefore beincreasingly impeded as the cathode moves closer to the aperture. Thiswill alter the pressure and rate of air flow through the air senser. Asthe grid-cathode spacing approaches the desired value, which ispreviously determined by t-he setting of photo-diode on the periphery ofthe air senser, see Figs. 10 and 11, the pointer 124 will begin to move.When the pointer reads the proper spacing, the light from lamp 126 will,as previously described, be reflected from the mirror 128 into thephoto- This will change the grid bias on tube 255, increasing itscurrent flow and actuating relay 274 and in turn closing relay 275. The

closing of'relay 275 accomplishes the following: (a) .relay contactor #1applies B+ to the welding circuit, thus chargingthe welding dischargecondenser 282, (b) relay contactor #2 disconnects the low forward speedmagnetic cuitis provided to delay the step switch a short time beforethe 'step switch is advanced to the weld firing position. Bank #5connects power'to the timing circuit and bank #4 establishes a circuit,through open relay 286 to'the stepswitch coil 300. The condenser 288 ofthetiming' circuit comprising relay 286, condenser 288, res'istor'290andrectifier 292 acts as a short circuit when 'power is first applied tothe-circuit by bank #5, and relay 286, therefore, which is in parallelwith the condenser 288 cannot close. In a short time, however, thecondenser charges, there is now a voltage drop across it and the relaycloses. Thisapplies the voltage from bank #4 to the step switch coil'300to advance it to position #5.

The-short delay achieved by means of a condenser of the order of 300-400microfarads is all that is needed to dela'y theswitch advance thedesired time.

Step switch: position #5.In this position, bank #6 applies -A.'C.*voltage to relay 278, closing it and thereby discharging theweld'storage condenser through the gridcathode assembly. The fingers 22of the retainer ring 18 are now firmly welded to the wall 24 of grid cupat the proper gridcathode spacing. Bank #5 energizes the step actuatingcoil 300, advancing the step switch to position"#6.

Step "switch position #6.In thisposition the photodiode light 126 andthe weld air solenoid 116 are cut out by bank #2. The rollers 104 aretherefore retracted from grid-cathode assembly. Bank #3 deenergizes thephoto-diode amplifier tube 255. The brake is now off since thezrelay275,now open, 'deenergizes the magnetic brake clutch 216.

' Bank #4 energizes the reverse magnetic clutch 214 and the lead screwshaft is now driven in reverse speed at 64 'R. P..M.

Bank #5 establishes a circuit through open limit switch 89 so that when.the .lead screw shaft 66 hastraveled far enough in the reversedirection to close it, see Fig. 8, a voltage will be again applied tostep switch coil 300 to advance the step switch to position #7. In itsreverse travel, the lead screw 66 first opens limit switch .91 and then,.a shortdistance further, closes limit switch 89, thus advancing .thestep switch to position #7.

.Position'#7 merelyreturns thestep switch to position #1 ready to repeatthe sequence of operations.

The push-rod 63, Figs. 7 and 8, may now be retracted, the completedgrid-cathode assembly removed from the adapter head, and a new assemblyloaded therein for the next operation.

Thus is disclosed a novel apparatus and method for manufacturing andspace checking grid-cathode assemblies which eliminates a great numberof disadvantages of the prior art. While certain aspects of theinvention have been described with particularity, it is apparent thatvarious changes and modifications may be made without departing from thespirit of the invention or the scope of the appended claims.

Having thus described the invention, what is claimed as new is:

1. Apparatus for automatically positioning two parts of an electron gunwith respect to each other comprising means for holding-said parts, apositioner engaged by one of 'said parts to restrain it against motion,meansfor engaging the second part and moving it with respect to thefirst part, means for sensing the relative displacement between saidparts, and means under control of the sensing means for arresting themotion of said moving means.

2. Apparatus for automatically positioning two parts of an electron gunwith respect to each other comprising means for holding one of saidparts, means for moving the second part with respect to the first partat a relatively fast rate of speed, means under control of said movingmeans for changing the rate of speed from said fast rate to a slowerrate, sensing means for sensing the relative displacement of said parts,and means under control of the sensing means for disabling the forwardmotion of said moving means.

3. Apparatus for automatically positioning'two parts of an electron gunwith respect to each other comprising means for holding one of saidparts, means for moving the second part with respect to the first partat a relatively fast rate of speed, means under control of said movingmeans for changing the rate of speed from said fast rate to a slowerrate, sensing means for sensing the relative displacement of said parts,means under control of the sensing means for disabling the forwardmotion of said moving means, and means also under control of the sensingmeans for etfecting a rapid reverse movement of the moving means.

4-. Apparatus for automatically positioning two parts of an electron gunwith respect to each other comprising means for holding one of saidparts, means for moving the second part with respect to the first partat a relatively fast rate of speed, means under control of said movingmeans for changing the rate of speed from said fast rate to a slowerrate, sensing means for sensing the relative displacement of said parts,means under control of the sensing means for disabling the forwardmotion of said moving means, and means for manually moving that portionof the moving means which is engageable with the holding means.

5. Apparatus for automatically positioning two parts of an electron gunwith respect to each other comprising means for holding one of saidparts, means for moving 'the second part with respect to the first partat a relatively fast rate of speed, means under control of said movingmeansrfor changing therate of speed from said fast rate to a slowerrate, sensing means for sensing the relative displacement of said parts,means under control of the sensing means for disabling the forwardmotion of said moving means, and means for manually advancing andretracting at least a portion of the moving means respectively towardand away from the holding means.

6. Apparatus for automatically positioning two parts of an electron gunwith respect to each other comprising means for holding one of saidparts, means for moving the second part with respect to the first partat a relatively fast rate of speed, means under control of said movingmeans forchanging the rate of speed from said fast rate toa slower rate,sensing means for sensing the relative displacement of said parts, meansunder control of the sensing means for disabling the forward motion ofsaid moving means, and means also under control of said sensing meansfor arresting the forward motion of said moving means.

7. Apparatus for automatically positioning and welding two parts of anelectron gun with respect to each other comprising means for holding andadvancing both of said parts, a positioner engaged by one of said partsto restrain it against further motion, means for moving the holdingmeans for continuing to advance the second part thereby varying thespacing between said parts, means for sensing said variation in spacing,and means under control of said sensing means when said spacing attainsa predetermined value for arresting the relative motion of the parts andfor welding said parts to each other.

8. Apparatus for automatically positioning and welding two parts of anelectron gun withrespect to each other comprising meansforholding andadvancing both of said parts, a positioner-engaged by one of saidpartsto restrain it against further motion, means for moving the holdingmeans for. continuing to advance the second part thereby varying thespacing between said parts, means for sensing the relative. displacementbetween said parts, means under control of the sensing means forarresting the motion of said moving means, and a movable welderelectrode also under-control of said sensing means mounted to movetoward and away from said parts to thereby weld said parts together.

9. Apparatus for automatically positioningand welding two parts of anelectron gun with respect to each other comprising, a guideway, meansfor holding said parts in said guideway and for advancing both of saidparts therealong, a positioner at one end of said guideway andengageable by one of saidparts to restrain it against motion, means formoving the second part with respect to the first part to vary thespacing between said parts, means for sensing said variation in spacingbetween said parts, and means under control of said sensing means whensaid spacing reaches a predetermined value for arresting the relativemotion of said parts, for welding said parts to each other, and forreversing the movement of said moving means.

10. Apparatus for automatically positioning and welding two parts of anelectron gun with respect to each other comprising a guideway, means forholding said parts in said guideway and for advancing both of said partstherealong, means for moving said holding means along said guideway, apositioning means at one end of said guideway engageable by one of saidparts to restrain it against motion to thereby effect a change inspacing between said engageable part and said other part, means forchanging the rate of advance of said holding means and one of saidparts, means for sensing the change of spacing between said parts, andmeans under control of said sensing means for disabling and arrestingthe motion of said moving means, for welding said parts to one another,and also for effecting a direction of movement of said moving means awayfrom said positioning means.

11. Apparatus for automatically positioning and welding two parts of anelectron gun with respect to each other comprising means for holding andadvancing both of said parts, a positioner engaged by one of said partsto restrain it against further motion, means for moving the holdingmeans for continuing to advance the second part thereby varying thespacing between said parts, means for sensing said variation in spacing,and means under control of said sensing means when said spacing attainsa predetermined value for disabling and for arresting the forward motionof said moving means, for welding said parts to one another, and alsofor causing said moving means to travel in a direction opposite to saidforward motion.

12. Apparatus for automatically positioning two parts of an electron gunwith respect to each other comprising means for holding said parts, apositioner engaged by one of said parts to restrain it againstmotion-means for moving the second part with respect to the first'part,said moving means including a first axially movable hollow shaft havinga first slot in an axial directionin'the wall of said shaft and a secondslot portion at one end of said first slot portion at an angle theretoand communicating therewith, a second shaft disposed coaxially withinsaid first shaft and extending beyond both ends of said first shaft andmovable therein, said secondjshaft having a pin extending above thesurface thereof and ada ated to ride in said first and second slots ofsaid first shaft, and means to drive said first and second shafts in anaxial direction.

13. Apparatus for automatically positioning twog parts of an electrongun with respect to each other and one of which parts is perforated andfor determining the spacing therebetween comprising a positioner engagedby one of said parts to restrain it against motion, means for moving thesecond part with respect to the first part, a holding means for saidparts including a first member having an inturned flange portion, andgrasping means exterior of said flange portion for holdinglsaid parts,

.with the perforated part within the flange portion, a second memberwithin the first member. and in telescopic relation therewith, acompressible ring between an end of said second member and said flange,means for longitudinally moving said second member with respect to saidfirst member to compress said ring and form an air tight seal aroundsaid perforated part, a passageway extending longitudinally through thesecond member and terminating in an air outlet at the said end of saidsecond member, said passageway extending to an air inlet port near theother end of said second member, air pressure .sensing means, and an airline between said sensing means and said air inlet port.

14. Apparatus for automaticallypositioning two parts of an electron gunwithrespect to each other comprising holding means for said parts, apositioner engaged by one of said parts to restrain it against motion,means for moving the second part with respect to the first part,including a rotatable shaft connected to drivesaid holding means andhaving a helical screw surface adapted to engage a mating screw surfacein a fixed member'to thereby impart a component of axial travel to theshaft,

a pulley secured to said shaft, means to drive said "pulley, a leverhaving a roller mounted on one arm thereof and riding on' a side of saidpulley, means acting on said lever to hold said roller in contact withsaid pulley, and a switch in the path of movement of the other arm ofsaid lever to be actuated thereby to control the movement of the pulleydriving means.

References Cited in the file of this patent UNITED STATES PATENTS I2,266,566 Poole Dec 16,1941 2,380,357 Ziebolz Iuly'lO, 1945 2,581,997Beggs "Jan; 8, 1952 2,585,533 Bryant et al Feb. '12, 1952 2,611,676Pohle Sept. 23, 1952

